You can start by find($String,'}') to find the position of the first ending bracket en then substring($String,0,X) where X is the position you found to parse the first line, then
Should give you the position of the next line and you can start using substring again to keep parsing the lines
Edit: With find($String,'
You should be able to find the position of the next line, this position should give the position of the last character of the previous line. I just tested this with a simple 2 line string. If you substring 0,X where X is the number you find above, you should be able to get the complete first line.
Stuart, just a thought - would it be possible to switch the string to an html format so that you can use an explicit <br> line break? It depends how it is being generated and what you want to use it for next...